1. Field of the Invention
The present invention relates to a performance evaluation apparatus for evaluating the performance of a motion mechanism of an NC machine tool, and a performance evaluation system equipped with the same.
2. Description of the Prior Art
In the prior art, when designing a machine tool, it has been practiced to physically produce a trial product based on designed results, evaluate whether the intended functions and performance have been obtained by using the machine tool, and determine the shape and specification of the machine tool as a final product by repeating design changes and trial production until satisfactory results are obtained. Accordingly, the prior art has had the problem that product development takes a long time, leading to an increase in development cost and resulting in a reduction in development efficiency (design efficiency).
To solve this problem, the recent trend is to employ techniques called digital engineering (design techniques implemented by a three dimensional CAD system using a geometric model, three dimensional model analysis techniques implemented by a CAE system, etc.) and perform the design and analysis work based on virtual models wherever possible, thereby minimizing or completely eliminating the physical production of trial products and accomplishing product development in a short time.
However, development using such digital engineering techniques has had the following problems.
That is, in the case of three dimensional model analysis using a computer, the evaluation result obtained from the three dimensional model analysis may not agree with the evaluation result obtained by actually producing a trial machine tool, because of the constraint that the evaluation can be done only under greatly limited analysis conditions or that there is a limit to the degree of accuracy to which the three dimensional model can approximate the actual machine. As a result, there have been cases where satisfactory results cannot be achieved in terms of the shortening of development time, the reduction of development costs, and the improvement of development efficiency which are the intended goals of the digital engineering.
Furthermore, when performing the three dimensional model analysis, analysis conditions assumed in actual use of the machine tool are used but, in actual use of the machine tool, the machine tool may be used under conditions or environments other than those assumed for the analysis, making it difficult to set conditions for the three dimensional model analysis, and on top of that, there are analysis conditions not readily computable; as a result, the evaluation result of the analysis may not agree with the result of the evaluation of the actual machine tool under all use conditions.
The present invention has been devised in view of the above situation, and an object of the invention is to provide a machine tool performance evaluation apparatus configured to efficiently collect and accumulate analysis conditions, etc. for use in three dimensional model analysis, and a performance evaluation system equipped with such the apparatus.
The present invention which achieves the above object concerns a machine tool performance evaluation apparatus that is provided for an NC machine tool equipped with a numerical controller for controlling operation of a motion mechanism in accordance with an operation command signal, and that evaluates performance of the motion mechanism, comprising:
analysis data storing means for storing three dimensional model data of the motion mechanism and condition data for performance analysis;
detecting means for detecting actual performance of the motion mechanism of the NC machine tool;
analyzing means for analyzing the performance of the motion mechanism, based on the operation command signal in the numerical controller and on the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means;
data accumulating means for storing actual performance data of the motion mechanism detected by the detecting means and performance analysis data analyzed by the analyzing means; and
evaluation determining means for evaluating the correctness of the performance analysis data by comparing the performance analysis data with the actual performance data of the motion mechanism stored in the data accumulating means.
According to this performance evaluation apparatus, first the analyzing means analyzes the performance of the motion mechanism, such as thermal deformation or deformation due to load, based on the operation command signal in the numerical controller and on the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means, and the analyzed performance data is stored in the data accumulating means. On the other hand, the actual performance of the motion mechanism is detected by the detecting means, and the thus detected actual performance data is also stored in the data accumulating means. Next, the evaluation determining means evaluates the correctness of the performance analysis data by comparing the performance analysis data with the actual performance data of the motion mechanism stored in the data accumulating means.
Here, various types of sensor such as a temperature sensor, displacement sensor, acceleration sensor, etc. are used as the detecting means, and a technique such as a finite element method or boundary element method is used as the technique for analysis. The method of evaluating the correctness of the performance analysis data is not specifically limited, but in one example, the evaluation can be done by computing the difference between the performance analysis data and the actual performance data and by determining whether the difference falls within predetermined tolerance limits.
In this way, according to the machine tool performance evaluation apparatus described above, since the correctness of the performance analysis data is evaluated by the evaluation determining means, not only can the reliability of the performance analysis data be confirmed, but the reliability of the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means can also be confirmed.
The present invention also concerns a machine tool performance evaluation apparatus further comprising data updating means for updating, in accordance with the result of the evaluation in the evaluation determining means, the data stored in the analysis data storing means so that the performance analysis data becomes correct when the evaluation result shows that the performance analysis data is not correct.
According to this performance evaluation apparatus, when the evaluation result shows that the performance analysis data is not correct, the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means are appropriately changed and updated by the data updating means so that the performance analysis data becomes correct.
In this way, according to this invention, since the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means are appropriately changed and updated so that the performance analysis data becomes correct, highly reliable three dimensional model data and condition data that match the actual machine can be efficiently obtained, and the accuracy of analysis can be enhanced.
The present invention also concerns a performance evaluation system constructed by connecting the above performance evaluation apparatus to a management apparatus via a network, wherein
the management apparatus comprises analysis data accumulating means for accumulating the three dimensional model data of the motion mechanism and the condition data for performance analysis, and
the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means and updated by the data updating means are transmitted at regular or irregular intervals to the management apparatus via the network and accumulated in the analysis data accumulating means.
According to this performance evaluation system, the three dimensional model data of the motion mechanism and the condition data for performance analysis stored in the analysis data storing means and appropriately changed and updated by the data updating means are transmitted at regular or irregular intervals from the machine tool performance evaluation apparatus to the management apparatus via the network and accumulated in the analysis data accumulating means provided in the management apparatus.
In this way, according to this performance evaluation system, correct and reliable three dimensional model data and condition data for performance analysis that accurately describe the performance of the NC machine tool can be efficiently collected and accumulated.
When designing a machine tool, if three dimensional model analysis is performed using the three dimensional model data and condition data stored in the analysis data accumulating means, the analysis can be performed extensively even with condition data not assumed or not readily computable in the prior art, and as a result, the accuracy of analysis can be enhanced and the evaluation result of the analysis can be brought closer to the evaluation result of the actual machine tool. Accordingly, satisfactory results can be obtained in terms of the shortening of development time, the reduction of development costs, and the improvement of development efficiency which are the main goals of digital engineering and which could not be achieved with the prior art.
The motion mechanism in the present invention collectively refers to the mechanisms constituting the machine tool excluding the controller, and includes: structures such as a bed, table, spindle, head stock or spindle head, saddle, and column; a feed mechanism comprising a feed screw, nut, feed motor, etc.; a spindle motor; and peripheral devices such as a tool changer and a pallet changer.